Bandgap and dimension regulation of CsPbI3 perovskite through a bromine-terminated ligand for efficient pure red electroluminescence

Single-halogen CsPbI3 is a promising candidate for red light-emitting diodes due to its high photoluminescence quantum yield, narrow emission line width, and facile solution processability. However, the bandgap of CsPbI3 is not in the range of the display-oriented pure red band (620-660 nm). In this study, the introduction of a phenylbutylammonium bromide (PBABr) ligand can not only tune the bandgap of the resulting low-dimensional CsPbI3 films but also induce the formation of a concentrated quantum-well structure at n = 3 domains, which contributes to better energy transfer and charge transport. As a result, low-dimensional PBABr capped CsPbI3 films with tunable emissions covering the pure red band were obtained and the corresponding efficient electroluminescent devices were achieved. By further optimizing the device structure and interface, a highly efficient red (653 nm) light-emitting diode device was fabricated with a maximum EQE of 14.3% and a maximum brightness of 543 cd m(-2). This work provides a facile one-step strategy by bromine-terminated ligand treatment to realize low-dimensional CsPbI3 films with desirable optical properties and preferred quantum-well distribution for display applications.